Can Engine Coolant Be Replaced with Mineral Water?
3 Answers
In emergency situations where antifreeze is unavailable, purified water or mineral water can be added, but tap water should be avoided if possible. Here are the relevant details: 1. Hazards: Mineral water not only increases the freezing point of the coolant but also causes chemical reactions between its minerals and the components of the coolant, affecting functions such as anti-boiling, anti-corrosion, anti-scaling, and lubrication of the cooling system. 2. Post-addition Handling: It is recommended to replace the coolant entirely. If the coolant level is sufficient but gradually decreases during use, and this is not due to leakage, there is no need for concern. You can directly add purified or distilled water to the coolant, but tap water or river water must never be used.
I've been driving for decades and have encountered many minor issues. Once during a long trip, the coolant was low, and to save trouble, I added some mineral water. Later, the car frequently overheated, and upon inspection, it was found that the radiator was severely corroded inside—it turned out mineral deposits had clogged the pipes. The engine cooling system is designed to use a proprietary fluid, with ethylene glycol added for freeze and boil protection, as well as rust inhibitors to protect metal components. Mineral water contains calcium and magnesium ions, which can form scale under prolonged high temperatures, leading to corrosion. I recommend checking the fluid level regularly and topping it up with the matching coolant if it's below the standard. In an emergency, distilled water can be used. Don't risk major damage for minor savings, as the repair costs can be very high.
Back when I was young and just bought a car, I also thought about trying to add mineral water to the coolant, thinking it would save effort and money. But later I realized it was too risky—mineral water contains impurities that can form scale in high temperatures, clogging the radiator and reducing cooling efficiency. Coolant can raise the boiling point and lower the freezing point, which ordinary water can't do. Protecting the engine is key; otherwise, it can easily overheat and get damaged. I recommend going to an auto parts store to buy the original brand coolant as per the manual, as mixing different brands may cause incompatibility. If you add the wrong thing, flush the system immediately. Drive worry-free for longer.
